The present invention relates to a driving device, a backlight with the driving device and a driving method of the backlight.
Thin film transistor liquid crystal display (TFT-LCD) is a one of popular flat display devices in the current market. TFT-LCD typically employs a backlight for providing a light source for the display. Most of backlights in the TFT-LCD use cold cathode fluorescent lamp (CCFL), which has advantages such as high brightness, low manufacturing cost, simple driving method and slim sizes, but also suffers from the potential environmental issue due to poisonous mercury material contained in the CCFL. Therefore, light emitting diode (LED) as an environment friendly device without mercury is more popular over CCFL also thanks to benefits such as low power consumption.
FIG. 1 is a schematic diagram showing a conventional driving device for LED backlight. As shown in FIG. 1, the driving device 1 is used for driving a LED backlight 2 with a plurality of LED units, or a plurality of strings of LED elements. The driving device 1 comprises a light modulation module 11 and a control module 12. The light modulation module 11 can control the overall current of the LED backlight according to external signals such as digital pulse width modulation (PWM) signal. The control module 12 can receive an external VIN signal and adjust output voltage of the driving device 1 accordingly to stabilize the output voltage. In the conventional driving device, the light modulation module 11 and the control module 12 can only control the overall current or voltage for the backlight. This might affect uniformity of brightness of the LED backlight if there is a discrepancy among the a plurality of strings of LED elements.